The audio settings are "OSS Audio Driver" and "Intel AC97". Now, I did notice that alsa 1.0.25 removed OSS support. So I switched audio to "ALSA Audio Driver", but still get the warning. I also tried "Intel HD Audio" as audio controller, but it doesn't make any difference.

Some problem with Virtualbox's sound was caused by media-libs/libsdl which break the sound.. version 1.2.13-r1 works OK but I have this problem with version >=1.2.14-r6 and portage has only these new version.._________________Sorry for my English. It's not my native language and I'm still learning it.

So I went ahead and modified the libsdl 1.2.15 ebuild to remove the --disable-alsa-shared configure option, and re-emerged. Starting up vbox, I no longer got the popup. Windows even found new HD Audio hardware and installed the drivers, but the HD codec still not work (error code 10, whatever). Shutting down and checking machine settings, I went back to the ICH AC97 sound controller. Booted back into Windows, and guess what, sound is back.

Thanks for the hint about libsdl, I don't think I would have found that.

Thanks for pointing me to bug report and show your solution.. I edit ebuild and upgrade libsdl and it works for my either.. Using ICH AC97 sound controller in VB 4.1.10._________________Sorry for my English. It's not my native language and I'm still learning it.

from what I understand, this is an issue of the bin package only and that the src is the same in the end, if so, why are you using the bin one?_________________Only two things are infinite, the universe and human stupidity and I'm not sure about the former - Albert Einstein
ProjectFootball

Another compile that taxes my machine to the limits. Gone are the days were 2GB of RAM could be considered sufficient.

gone are the days that dual core cpu is sufficient, gone are the days that non HD hw decoding gpu is sufficient, gone are the days that single core cpu is sufficient, gone are the days that 640k of ram is sufficient.

you cannot stop the progress, if it is doable, maybe it is time to upgrade your system or even get a new one._________________Only two things are infinite, the universe and human stupidity and I'm not sure about the former - Albert Einstein
ProjectFootball

Try to move from bin to source and run it in night with updates.. It takes

Code:

virtualbox: 1 hour, 1 minute, 45 seconds for 1 merges

on my Dell 6400 laptop (little old I know and I only dream about 2 GB of RAM, I have only half of that) but it works and compile with no problem.. So there are no reason to come back to bin.. I was little bit confused with PUEL and OSE version when I installed it for a first time (several years ago) but now I see that after version 4.0 there are only one edition (I didn't notice that change) and closed-source have been moved to extension pack._________________Sorry for my English. It's not my native language and I'm still learning it.

from what I understand, this is an issue of the bin package only and that the src is the same in the end, if so, why are you using the bin one?

If I recall right, only the 'bin' version supports USB 2.0.
Otherwise, if both versions are really identical, please let me know - maybe I'll move to the src one then._________________Did you know that we typically make use of only 5% of the power of our personal computers?
Check http://setiathome.berkeley.edu or http://www.seti.cat to use 100%!

Brilliant, it has also solved the problem for me, bazillions of thanks!

In case it helps, my setup is:
- kernel 3.4.9
- libsdl 1.2.15-r2
- virtualbox-bin 4.1.20
- In VirtualBox, the audio is set to ALSA and the controller to ICH AC97
- The vbox I have is Windows XP, with the audio detected as Intel 82801AA AC'97

Just in case some newbie passes by with this problem and doesn't know the details of the solution you've found:
1. Edit /usr/portage/media-libs/libsdl/libsdl-1.2.15-r2.ebuild, just removing the line that says:
--disable-alsa-shared \
2. Edit /usr/portage/media-libs/libsdl/Manifest, updating the line of the ebuild like this:
EBUILD libsdl-1.2.15-r2.ebuild 4112 SHA256 373b5b3fb7fd97aa0dd278fb0927b3fdb56118f58a7e44f6376b9edc99ce8988 SHA512 dad6ee545f731a7c6bfa41e2167386fe7e21fc12c408c14b0e6e982e04006c6488f7ed0feba509e77730d1c8649c51ac8a37e23d72ee50806123062727593e53 WHIRLPOOL 6d9d71472c5df5c9e1290e0f797621716cf23966a1ce6cd4b1f088f0232413cf1ad7bdecf7aa05f246666f9f1ef8f43a78fcf0112742a056d9e114d08aac61e2
3. Re-emerge libdsdl
4. Start VirtualBox and... voilà!!_________________Did you know that we typically make use of only 5% of the power of our personal computers?
Check http://setiathome.berkeley.edu or http://www.seti.cat to use 100%!

I've just realized that, although I can perfectly play sound from VirtualBox now, I cannot record!
My microphone simply doesn't work. And I need that for videoconferences (we have to use Marratech, only for Windoze... )
I've checked all the settings of the Windows mixer and its audio setup.
The mic works perfectly fine in the Gentoo host - I often use that with Skype.